The Upanishads describe 4 states of consciousness, the waking, the dream, the sleep and the state beyond these 3. Sri Aurobindo points out that these are meant to symbolically represent the state of awareness in the outer world (waking), the state of awareness in the subliminal world (dream), the state of awareness in the superconscient world (sleep) and the 4th state, is the one transcendent Reality.
The reason that the subliminal state is called the dream state is that is in fact the primary vehicle that most people have available to them to gain information from this subliminal realm of awareness. The other main entry is through the state of trance, and this is not generally accessible to the vast majority of people on a consistent basis.
Sri Aurobindo describes the relationship between waking and the subliminal consciousness as follows: “Our waking state is unaware of its connection with the subliminal being, although it receives from it,–but without any knowledge of the place of origin,–the inspirations, intuitions, ideas, will-suggestions, sense-suggestions, urges to action that rise from below or from behind our limited surface existence.”
“The subliminal, with the subconscious as an annexe of itself,–for the subconscious is also part of the behind-the-veil entity,–is the seer of inner things and of supraphysical experiences; the surface subconscious is only a transcriber.”
If one can enter into the yogic trance, and achieve the inner waking state, there can be a more direct and clear communication between the subliminal and the waking consciousness. If, however, this access occurs during sleep, then it tends to be figured in the images of dreams. Dreams in this case become “windows” to information that can and does influence the way we think and act in our waking lives, and thus, dreams are not simply to be dismissed as unreal or illusory. Understanding the role that dreams play in helping us access the wider awareness found at the subliminal level can provide us a tool of real value in our process of seeking and applying knowledge. It is no surprise that common wisdom holds that “sleeping on a problem or a decision” can lead to clarity…one wakes with the knowledge of what should be done… This represents the power of the subliminal providing us knowledge not easily seen or known by our limited waking awareness.
reference: Sri Aurobindo, The Life Divine, Book 2, Part I, Chapter 5, The Cosmic Illusion; Mind, Dream and Hallucination, pp. 426-427